Energy SPDR

The biggest energy ETF by far is the Energy SPDR (XLE) fund, which boasts $8 billion in assets.

Top holdings include Exxon Mobil (XOM), Chevron (CVX) and Schlumberger (SLB), with these three plays making up more than a third of the entire asset allocation. Sector-wise, the fund is about 79% in direct oil and gas plays, which include integrated oil stocks like XOM, and roughly 21% in energy equipment and service stocks like SLB.

The yield in this fund is slightly higher and the expenses slightly lower than its competitors, making it a top fund in the energy ETF space for good reason.